On-chip capacitors are common components of integrated circuits. These capacitors are used for a variety of purposes: illustrative examples include bypass and capacitive matching as well as coupling and decoupling. The design and implementation of capacitor structures in integrated circuits may be dependent upon one or more symmetrical structural, target circuit quality and low parasitic resistance performance characteristics.
Metal-Insulator-Metal Capacitor (MIMCAP) devices are one type of on-chip capacitor and are generally formed during back-end-of-line (BEOL) processing. In integrated-circuit fabrication lines, front-end-of-line (FEOL) conventionally refers to earlier process stages that directly modify the semiconductor substrate or the immediate contacts to it; for example, dopant diffusion and implantation, sputtering of gate films, oxidations, and the patterning steps associated with these. In contradistinction, the BEOL is metallization for interconnects and vias (vertical interconnects between planar interconnects) and associated non-conducting depositions and growths (for example, polymers, glasses, oxides, nitrides, and oxinitrides) for electrical isolation, dielectrics (for capacitance), diffusion barriers, and mechanical passivation (in particular, to prevent failure of interconnects by electromigration and stress migration). FEOL and BEOL are used to refer to the levels of an IC fabricated in the corresponding stages. BEOL is the metallization layers and associated insulating layers, and FEOL everything below that (mostly transistors).
It is often difficult to form MIMCAP devices that meet target minimum capacitance requirements at an applied voltage bias for the MIMCAP device while also achieving sufficiently long reliability lifetimes given constraints during BEOL processing. Optimal MIMCAP fabrication details and structure will in general depend upon the reliability lifetime requirements (typically in years), the magnitude of the applied voltage, and whether reliability is required for voltage drops across the device from top electrode to bottom electrode that are positive only, negative only, or either positive or negative (bi-directional).
Accordingly, it is desirable to provide integrated circuits including a MIMCAP and methods of forming the same with the MIMCAP having a specified reliability lifetime while still attaining a minimum target capacitance density at an applied voltage bias for the MIMCAP device. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.